A display panel includes a plurality of pixels arranged in an array, each pixel is provided with a light-emitting diode (such as, an organic light-emitting diode (OLED)) and a driving transistor for driving the light-emitting diode to emit light. A magnitude of a driving current for driving the light-emitting diode is related to a threshold voltage of the driving transistor. In order to avoid an influence of the threshold voltage drift of the driving transistor on display brightness, the threshold voltage of the driving transistor needs to be detected, so as to compensate a data signal according to the threshold voltage during a driving process.
Currently, detecting the threshold voltage of the driving transistor may comprise: connecting a source electrode of the driving transistor to an analog-to-digital converter (ADC); applying a data signal to a gate electrode of the driving transistor, applying a reference signal to the source electrode of the driving transistor, and applying a power signal to a drain electrode of the driving transistor, so as to turn on the driving transistor and output a current to the analog-to-digital converter; and when the driving transistor is in a turn-off state and stops to output the current, determining a threshold voltage of the driving transistor according to a gate voltage Vg (that is, a voltage of the data signal) of the driving transistor and a source voltage Vs detected by the analog-to-digital converter. The threshold voltage Vth of the driving transistor satisfies a formula: Vth=Vg−Vs.
However, during the use of the driving transistor, the threshold voltage of the driving transistor may drift due to an influence of factors such as process conditions and time of use, so that the source voltage on the source electrode of the driving transistor is changed accordingly. The source voltage may exceed a detection range of the analog-to-digital converter, and therefore the accuracy of the detected threshold voltage of the driving transistor is affected.